Evaluation and de-coupling of electrochemical and mechanical effects of diluted WCMP commercial slurry on tungsten removal rate

Electrochemical properties and removal rates of modified commercial WCMP slurries have been evaluated. Primarily, the influence of the pH and degree of dilution on the open circuit potential and corrosion current density of CVD tungsten film was investigated. CMP removal rate were measured under the same set of conditions. Relevant aspects of the electrochemical behaviour are highlighted and related to the polishing behaviour. The results of this study are relevant to the operative management of the WCMP process and corroborate the starting working principle that ex-situ characterization of basic parameters is a useful procedure for WCMP optimization.